The present invention relates to a disk device, for recording and/or reproducing information thereon, such as, a magnetic disk and/or an optical disk, etc., and it relates to, in particular, a disk device, being equipped with a balance adjustment mechanism therein, thereby enabling suppressing of vibration generated when the disk-like recording medium rotates.
With a disk device for recoding/reproducing data on a rotating disc-like information-recording medium, such as, a magnetic disk device, for example, if vibration comes to be large due to rotation of primary swing-round, which is generated accompanying with rotation of the disk, there is a danger that errors occur in recording/reproducing operation of information on the disk. In particular, in recent years, the rotation speed of the disk comes up to be high for the purpose of improvement of transfer speed of data, and accompanying with this; therefore, it has a potential that the vibration of swing-round becomes large. For this reason, it comes to be more important than before, to reduce an amount of unbalance between the disk and a hub holding the disk thereon, thereby reducing the swing-round vibration thereof.
On the other hand, in the conventional art, in general, it is conducted by attaching a balance weight onto the hub, holding the disk(s) thereon and rotating together with, thereby reducing an amount of unbalance thereof. For example, a balance weight (a stop ring) being “C”-like in the outer configuration thereof, is attached on an inner periphery surface of a concave portion, which is formed in a part of the hub mentioned above (e.g., on both end surfaces in a direction of rotation shaft thereof). Further, the balance weight (or the stop ring) is a little bit larger in the diameter thereof than the inner diameter of the hub mentioned above, and therefore, it will not come out nor be shifted in the position thereof when the hub rotates at a high speed. However, according to such the method of fitting each of the balance weights into each of the surfaces, it is difficult to make adjustment on an amount of unbalance, in particular, when a specification required for balance comes to be strict, accompanying with the high-speed of the disk rotation, it is impossible to cope with or satisfy such the requirement, sufficiently.
Namely, in order to attach the balance weight onto the hub, it is necessary to form a ring-like groove, in a portion of the hub, around the rotation center thereof. And, for each of the balance weights, one (1) piece of groove is necessary in a circular-like shape, therefore a plural number of the circular-like grooves must be formed when attaching the balance weights in a plural number thereof. Further, by taking a repair on the apparatus into the consideration, it is also necessary to form the grooves, but further more in the number than that, with separating them from each other thereon, so as to ensure sufficient spaces for attaching and removing the balance weights, in particular, when making repair on the apparatus. Accordingly, it is difficult to ensure such the sufficient spaces for mounting or attaching the balance weights thereon.
Then, with the conventional art that is shown, such as, in Japanese Patent Laying-Open No. Hei 11-353788 (1999), for example, there is already proposed a magnetic disk device equipped with a balance adjustment mechanism therein. Thus, according to this conventional art, the balance weights (or the stop rings) in the “C” shape are attached on an inner periphery surface of the hub, piling at least two (2) pieces thereof up and down.
Further, with the balance correction mechanism according to this conventional art, a plural number (e.g., two (2) pieces) of the balance weights are fitted or inserted, while shifting the position thereof from one another, when being attached. With this, since an unbalance vector for correction can be formed through addition of the unbalance vectors in a plural number of the balance weights, it is possible to obtain the unbalance vector for correction, having an arbitrary magnitude thereof, but without increasing a number of types or shapes of the balance weights.
In more details, the balance weights, according to the conventional art mentioned above, are attached on the hub, so that the rotation center of the hub comes into an inside of a circle defined by the outer configuration thereof. This is for the purpose of preventing the balance weights from coming out due to the centrifugal force generated at the high rotation speed. And, this “C” shaped balance weight is inserted into from an inside of the hub, being suppressing a little bit into an inside thereof from a condition of non-load thereupon, therefore it is possible to ensure or keep a holding force of the balance weight even when it is not rotated, and also, it acts in a direction to enhance the holding force when the centrifugal force is generated due to the rotation thereof. Since the balance weights of the “C” shape are attached, being compressed a little bit into the inside so as to prevent it from coming out even in the non-rotation condition, it is manufactured to define an arc being equal or greater than 180 degrees in the central angle thereof.
However, with such the balance weights according to the conventional art mentioned above, it has a problem from a viewpoint of the space for mounting or attaching thereof, and it is impossible to adjust or correct the balance at high accuracy. Namely, it is the structure of fitting a plural number (e.g., two (2) pieces) of the balance weights, and the grooves must be formed to be deeper, comparing to that for receiving one (1) piece of the balance weight therein, therefore, though depending on the structure thereof, it is impossible to form such the deep grooves in the hub, thereby resulting into a case where they cannot be attached thereon.
Also, as was mentioned in the above, as the requirement becomes much strict to the specification for balance, it can be considered that a type of balance weight be adopted, mainly, with which the balance weights are fitted in a plural number thereof, with shifting the position thereof from each other, however in a case when trying to perform the balance correction at high accuracy, in particular, applying an embedding method therein, in which the balance weights cannot be removed from after once being mounted thereon, for ensuring the space, in particular, it is necessary to correct or adjust an angle of attachment of those balance weights. However, in that instance, the balance weights must be slid with respect to the hub, or the one of the balance weights must be slid to the other one thereof, but fine particles or dusts are generated during the time of such the work. But, such the fine particles or dusts are formidable to the magnetic disk to which the represent invention relates, and then it is absolutely impossible to adopt such the method or technology.
In addition thereto, since attachment of those balance weights are conducted after determining the position thereof, while rotating it by a motor, then sufficient accuracy cannot be obtained, and for this reason, the correction vector fluctuates in the magnitude thereof. Although depending upon the specification for balance, but if such the fluctuation occurs in the magnitude of the correction vector, there may be a risk of bringing the balance of the disk to be unable to correct.